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This study presents a novel boron‐difluoride complex‐based fluorescent nanofilm sensor capable of detecting sarin vapors in the environment by reporting an output fluorescence signal. The sensor's evaluation demonstrated an exceptionally low detection limit for sarin vapor, even in the presence of various interfering gases, with theoretical and practical limits of detection of 0.7 and 1 ppb, respectively. The sensor featured a rapid response time (less than 2 s), a broad linear detection range (1 ppb–1000 ppm), and superior selectivity for sarin vapor over a group of interfering analytes, outperforming existing sarin sensors. Mechanistic study indicates that the sensor's heightened sensitivity to sarin vapor is due to the robust affinity of nitrogen atoms within the core BODIQ unit for sarin. Additionally, the tetraphenylethylene structure with steric hindrance effectively inhibits the tight packing of BODIQ derivatives, and forms numerous microporous structures in the self‐assembled nanofilm, which are beneficial for the mass transfer, enhancing the sensor efficiency in detecting vapors. Furthermore, we have achieved the differentiation of sarin, diethyl chlorophosphate, and HCl vapor through the analysis of sensing kinetic. This fluorescent sensor opens new avenues for sustainable, low‐cost, and environment‐friendly portable devices, as well as for environmental monitoring and tracking applications. [ABSTRACT FROM AUTHOR]

Solvothermal synthesis is the predominant method for creating new structured covalent organic frameworks (COFs), yet it grapples with challenges in controlling shape and morphology. This issue is attributed to the unregulated solvent‐feeding process, which results in rapid polymerization and uncontrolled phase separation. Consequently, a two‐step solvent‐feeding process is reported for the solvothermal shaping of imine‐linked COF monoliths with hierarchical porosity. The synthesis conditions for COF powders reported in existing literature are directly utilized without extensive optimization; however, solvents are divided into two segments prior to feeding. A minor segment of solvents is employed to dissolve monomers, which polymerize in situ to form amorphous monoliths. Subsequently, the remaining organic solvent, along with an acetic acid aqueous solution, is added for crystallization. The versatility of this two‐step feeding process in producing COF monoliths is illustrated. The high‐quality COF monoliths demonstrate benzene uptakes ranging from 6.0 to 16.8 mmol g−1 at 298 K. This study confirms that the two‐step solvent feeding process can be effectively integrated with the conventional solvothermal method to enhance the solution‐processability of COFs. It is anticipated that this modified solvothermal approach can readily shape COFs to meet practical application requirements. [ABSTRACT FROM AUTHOR]